Dascher C, Balch W E
Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92130, USA.
J Biol Chem. 1996 Jul 5;271(27):15866-9. doi: 10.1074/jbc.271.27.15866.
Members of the syntaxin gene family are components of protein complexes which regulate vesicle docking and/or fusion during transport of cargo through the secretory pathway of eukaryotic cells. We have previously demonstrated that syntaxin 5 is specifically required for endoplasmic reticulum to Golgi transport (Dascher, C., Matteson, J., and Balch, W. E.(1994) J. Biol. Chem. 269, 29363-29366). To extend these observations we have now cloned a protein from rat liver membranes which forms a native complex with syntaxin 5. We demonstrate that this protein is the mammalian homologue to yeast Sly1p, previously identified as a protein which genetically and biochemically interacts with the small GTPase Ypt1p and Sed5p, proteins involved in docking/fusion in the early secretory pathway of yeast. Using transient expression we find that overexpression of rat liver Sly1 (rSly1) can neutralize the dominant negative effects of excess syntaxin 5 on endoplasmic reticulum to Golgi transport. These results suggest that rSly1 functions to positively regulate syntaxin 5 function.
syntaxin基因家族的成员是蛋白质复合物的组成部分，这些复合物在货物通过真核细胞分泌途径运输过程中调节囊泡对接和/或融合。我们之前已经证明，内质网到高尔基体的运输特别需要syntaxin 5（Dascher, C., Matteson, J., and Balch, W. E.(1994) J. Biol. Chem. 269, 29363 - 29366）。为了扩展这些观察结果，我们现在从大鼠肝细胞膜中克隆了一种与syntaxin 5形成天然复合物的蛋白质。我们证明这种蛋白质是酵母Sly1p的哺乳动物同源物，酵母Sly1p先前被鉴定为一种在遗传和生化上与小GTP酶Ypt1p和Sed5p相互作用的蛋白质，Ypt1p和Sed5p是参与酵母早期分泌途径中对接/融合的蛋白质。通过瞬时表达，我们发现大鼠肝脏Sly1（rSly1）的过表达可以中和过量syntaxin 5对内质网到高尔基体运输的显性负效应。这些结果表明rSly1起到正向调节syntaxin 5功能的作用。
